hinge tension adjustment

[dcouzin]

Is there an easy way to adjust the hinge tension on the T4x?
Mine are too tight since a some repair work, and I'm afraid I'll break a hinge unless I open and close the lid oh-so-slowly.
Thanks.

[Harryc]

There is no adjustment. Replacement is the only option.

[dcouzin]

Horrors! Can you explain how the drag is produced in the hinge? Can I bend a spring or change a lubricant?

[Harryc]

There is no adjustment, no lubrication. It works by internal friction between parts of the hinge.

[rtrimble]

I can't believe there is no way to lubricate or adjust the tension on the hinges. I bought a refurbished T41p from Lenovo, and the left hinge broke 6 months later. (Yeah, out of warranty.) I bought a replacement and managed to install it (what a job!), but it was extremely stiff, and the lid made popping and snapping noises when opened or closed. The old one never did that, so I hoped it would wear in with time, but instead the metal bracket gave out after two months. I assumed it must have been a defect in the hinge, and bought a new one from a different dealer. Dozens of tiny screws and hours of work later I now have that one installed, and it is doing exactly the same thing.

These things cost less than $20 but, much as I like the machine, I'm not about to shell that out several times a year, not to mention the labor, not to mention the embarrassment of the loud SNAP, SNAP noises when I open, close, or adjust the lid in Starbucks.

[dcouzin]

Harryc's answer that "There is no adjustment, no lubrication / It works by internal friction between parts of the hinge" raises the question: Why can't the friction between parts be modified by lubrication between those parts?
Well, maybe the surfaces are already as lubricious as surfaces can be. Or maybe there's no way to get the lubricant in, especially after assembly. Or maybe no added lubricant will stay put.
Can rtrimble disassemble one of his removed hinges and tell us what rubs against what?

[rtrimble]

Well, I've tried, but I'm not sure how much I can contribute. Unfortunately the two removed hinges have already gone out in the garbage, but the replacements I ordered came in pairs, so I have two unused right-side hinges. I decided to sacrifice one to the cause of science. Physically the “hinge” part looks like a solid black shaft attached to metal pieces at each end.

When I started hacking at it I discovered that what appeared at first to be a hard black plastic shaft turned out to be two black-painted metal cylinders, 5 mm in diameter, butted together, with a thin plastic sleeve protecting the pivot point. One cylinder, about 8 mm long, is locked by a flattened shaft to the bracket which is bolted to the Thinkpad body. The other, about 5 mm long, is similarly locked to a long thin metal strip that runs all the way up the side of the screen.

The cylinders appear to be a high quality steel, as I have had little success against them with a saw or file. Obviously there must be something that holds them together, presumably a smaller shaft that extends from one into the other. I have not been able to pry them apart or find anything that could be unscrewed. (It can't be Jo block adhesion alone, since I can't slide them sideways, either.)

I do, however, see one intriguing feature. The body-side bracket has a cylindrical extension of the butted shafts, also 5 mm diameter. On its side is a tiny hole, about 0.5 mm in diameter, filled with something black.

Theory #1: It could be a lubricating hole.

Theory #2: It was a breathing hole to allow the smaller shaft, with some lubrication, to be inserted into the center of the other cylinder. The hole was then sealed to prevent the two parts from separating.

At this point my money's on theory #2.

[dcouzin]

rtrimble, thank you for the exposition on the hinge. As I understand it the friction arises from a lubricated metal shaft rotating in a snug metal bore. It's a case where there's no way to get the lubricant in after assembly. The tight dimensional and surface tolerances involved are an invitation to variation, and some hinges indeed have higher torques than others.
I didn't understand how the assembly is held together. Can you remove a too tight shaft and polish it smaller? But what if the laptop lid is too loose after that!
If you think about it, hinges are rarely relied on to be multiposition stays for lids or doors. Look at the elaborate constructions around automobile door hinges. Laptop design makes quite tough mechanical demands on the hinges, and it's no wonder they cost $20 and are still not up to snuff.

[RealBlackStuff]

The only thing you may be able to use, is creeping oil, like WD40.
Spray a lot into a plastic (lunch)bag, so you get enough liquid, then soak the hinge in that liquid for a while.

The left and right hinges are different in construction.
Using rtrimble's terminology, the black-painted metal cylinders are longer on the left side than on the right side.
IMHO this would cause more torque, and probably explain the more frequent breaking.

[rtrimble]

For dcouzin, I could have explained my theory #2 a lot better, sorry. The bore was, of course, filled with air before the shaft was inserted. Assuming a tight fit and a viscous lubricant, the air would be forced out the breathing hole during assembly. If that hole was then sealed, a vacuum effect in the bore would hold the pieces together. If I get a chance I may try to drill out the contents of the hole to test my theory.

By the way, corollary hypothesis #1: The reason these replacement hinges are so stiff is that they have been sitting around on shelves for years and the lubricant has dried out.

[sjthinkpader]

Due to the complex shape, the hinge bottom portion looks to be a plated powder metal pieces. The breakage point is a thin section in the left hinge. I had one replaced on my T41 when it was two years old..

The lubricant if any, seems to be dry since there are no leakage of any kind.

[dcouzin]

An uncommon grease, opposite to a damping grease. Its stiction (to hold the lid in place) should be high relative to its friction (which slows motion). http://en.wikipedia.org/wiki/Non-Newtonian_fluid. Whatever the drag curve may be, the laptop user must have the sense to control the lid velocity in order to limit the torque at the hinge.
We don't know if IBM chose a short life grease. Maybe all the spare hinges were made in the same batch, with a tighter fit. We don't know whether the hinges become stiffer over time, or whether the users become insensitive over time.
For example I broke my T42 hinge by abuse. I rapidly opened and closed the lid (for an unspeakably silly purpose) and after a minute of this the hinge snapped. Probably the grease heated causing its friction (or stiction) to increase.
I started this strand in April worried about my T42's stiff new hinge. I've adjusted to it. The hinge can take only so much torque and it's our job to sense that and not to exceed it.

[rtrimble]

My problem is that I am unable to control the instantaneous velocity. I push gently at first, and the lid hardly moves. I then increase the pressure gradually until SNAP, it jumps with a loud noise.

For sjthinkpader's benefit, as a Silicon Valley resident, I think of this as analogous to a certain trans-bay bridge joint under stress from the weight of the 50 foot span it supported. Twenty years ago this month it was suddenly jolted by a SNAP that occurred 60 miles away near Loma Prieta Peak. The joint failed, creating a steep ramp from the upper deck to the lower deck of the Bay Bridge. Back to my Thinkpad, yes, it is the bracket that breaks, where it is attached to the base, but I am convinced it is the sudden vibration originating deep within the two temporarily frozen hinge cylinders which triggers the failure.

[lead_org]

An uncommon grease, opposite to a damping grease. Its stiction (to hold the lid in place) should be high relative to its friction (which slows motion). http://en.wikipedia.org/wiki/Non-Newtonian_fluid.

I doubt that the hinge friction is caused by non-newtonian fluids, there is not enough of these liquids to make it work in a such a small space. That what i thought initially, but after thinking it through and reading some books on this matter and consulting our slurry and sludge expert (we have a lot of these non-newtonian fluid at the processing plant) at the mines, i have concluded that this is unlikely scenario.

[sjthinkpader]

...
For sjthinkpader's benefit, as a Silicon Valley resident, I think of this as analogous to a certain trans-bay bridge joint under stress from the weight of the 50 foot span it supported. Twenty years ago this month it was suddenly jolted by a SNAP that occurred 60 miles away near Loma Prieta Peak. The joint failed, creating a steep ramp from the upper deck to the lower deck of the Bay Bridge. Back to my Thinkpad, yes, it is the bracket that breaks, where it is attached to the base, but I am convinced it is the sudden vibration originating deep within the two temporarily frozen hinge cylinders which triggers the failure.

Yes, I remember that day, the monitor on my desk fell to the floor (still worked afterward). Water in the pond outside splashed out. It took two hours to get to my kid's daycare place that normally took 30 minutes. My middle daughter stood in the door way during the many aftershocks. My computer ran DOS, email was an IBM tool and we used fax everyday.

But there are a lot of other types of metal technology that are stronger. Strongest being forging. The complex shape dictated it be made out of powder metal for reasonable cost.

[rtrimble]

Final chapter (I hope) in this tale of woe. First, a quick summary:

* July 2009: Left T41 hinge broke, machine out of warranty. Ordered replacement pair from LaptopZ for $18.49. New hinge so stiff it almost appeared to be frozen. When installed it made SNAP! SNAP! noises no matter how gently I moved the lid.

* Sept 2009: New hinge broke. Ordered another from Silicon Valley Electronics for $16.45. Just as stiff as the first one.

Now for the new chapter:

Oct 2009: Once again, broken left hinge. As one last try, I went to the IBM web site. That sent me to Lenovo, where I could see the part, but could not find any way to order it. After 2 hours of various search requests on both websites, I finally got to a page (back at ibm.com) where I could put the part in a shopping basket. More frustration as the site refused to process my order using Firefox or Opera, despite bribing them with all the cookies they wanted. They liked Internet Explorer, and gave me a price of $60.23, including shipping and tax.

I gulped, and went ahead, and got a confirmation at that price ... followed the next day by an email from a guy in Argentina saying the price had gone up another $6.34. With smoke pouring out my ears, I gave a rather rude reply, but eventually changed my mind and said yes.

Nov 2009: The part arrived quickly, and I could actually move the hinge by hand before installing it! I just now put it in, and the lid works smooth as glass. (By the way, IBM included replacement stick-on screw "caps" - black covers - which was nice.)

Two bottom lines for any other poor soul with my problem:

1. If you can't move a replacement hinge by hand before installing it, send it back.

2. I guess you get what you pay for. Stay away from the under $20 guys. But you might try dealers in the $40 range rather than the incredible hassle I had with Big Blue.